The present disclosure relates to a modular sighting assembly for use with a weapon system. The present disclosure will be made herein primarily by way of reference to the preferred embodiment wherein the weapon is a grenade launcher, although it will be recognized that the present development is not limited to use with weapons of any particular type, size, munitions type, or caliber. The grenade launcher is preferably of the type that is attachable to a military or assault rifle such as an M-16 assault rifle, M-4 Carbine, or the like, although use with a standalone grenade launcher is also contemplated. Although, the present development is particularly advantageous for aiming firearms and artillery that launch or fire projectiles at relatively high elevation angles, the present development is not limited to such and can be used with any type of firearm or artillery that launches a projectile with a known trajectory. The terms “firearm” and “artillery” as used herein are intended to encompass all manner of weaponry, including without limitation, guns such as handguns and rifles, heavy caliber guns, grenade launchers, cannons, howitzers, mortars, rocket launchers, and the like.